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Regional Variation In Recruitment Of Hemlock Seedlings And Saplings In The Upper Great Lakes, Usa, Thomas P. Rooney, Ronald J. Mccormick, Stephen L. Solheim, Donald M. Waller Aug 2000

Regional Variation In Recruitment Of Hemlock Seedlings And Saplings In The Upper Great Lakes, Usa, Thomas P. Rooney, Ronald J. Mccormick, Stephen L. Solheim, Donald M. Waller

Biological Sciences Faculty Publications

Mature eastern hemlock–northern hardwood forest cover decreased drastically in the upper Midwest following European settlement and has yet to rebound substantially. Previous studies show that stands retaining substantial hemlock canopy coverage have low hemlock seedling and sapling densities. Results from various geographically restricted studies suggest several possible mechanisms that could cause low seedling or sapling density. We examined the relative importance of these proposed mechanisms in the Southern Superior Uplands Section of the Laurentian Forest Province. We surveyed 294- m2 plots in 100 hemlock stands in northern Wisconsin and western upper Michigan to assess how these proposed mechanisms affect the …


Applications Of Wavelet Transforms In Biomedical Optoacoustics, Zibiao Wei, Shujun Yang, Amin N. Dharamsi, Barbara Hargrave Jan 2000

Applications Of Wavelet Transforms In Biomedical Optoacoustics, Zibiao Wei, Shujun Yang, Amin N. Dharamsi, Barbara Hargrave

Biological Sciences Faculty Publications

We discuss the utility of wavelet transform methods in signal processing in general, and in particular, demonstrate the technique in optoacoustic applications. In several optoacoustic experiments with different samples, we have successfully enhanced the signal to noise ratios. Wavelet transforms optimize resolution by utilizing a tailored, variable time-window in different frequency regions. The technique's great advantage lies in the fact that the wavelet transform adds some redundancy to the original signal, and some desired features can be enhanced in the transformed space. In addition, proper choice of the basis set allows a sparse representation of the signal. Therefore, even when …